1. Field of the Invention
This invention relates to photographic apparatus, preferably cameras of the self-developing type, having an optical system capable of selectively geometrically reversing an image of a subject on a film plane along either one axis or along each of two orthogonal axes.
2. Description of the Prior Art
Certain photographic film materials are structured to directly record a positive image of any subject properly imaged and exposed thereupon. Exemplary of such materials are the film units described in U.S. Pat. No. 3,415,644, entiled NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES and issued to E. H. Land on Dec. 10, 1968. Film units of this type are intended for use within the above-noted self-developing or self-processing photographic cameras and incorporate all of the materials necessary to produce a positive photographic print immediately following their exposure. While being of a somewhat complex chemical makeup, the film units are physically structured to include a planar photosensitive element in laminar combination with a transparent image-receiving element. Specially packaged processing units are additionally included within the units. By virtue of the structural parameters of the film units identified above, the transfer image formed upon direct exposure of the film unit to a selected subject and processing will be a geometrically reversed image of the subject along one direction, e.g., the transverse direction of the film plane.
Accordingly, to provide transfer image formation geometrically non-reversed, exposure of the film unit should be accomplished through an appropriate image reversing optical system.
In order to accomplish such optical image reversing, previous cameras designed for use with such film units necessarily included one or an odd number of specular surfaces incorporated within the optical path extending from the camera lens to the exposure plane of a film unit. Because these film units are configured to provide a desirably large film format, certain improved photographic camera designs have taken advantage of the requisite specular surface to achieve somewhat compact overall camera structures.
Exemplary of such compact designs is a camera structure described in U.S. Pat. No. 3,699,865, issued Oct. 24, 1972 and entitled PHOTOGRAPHIC APPARATUS. This type of a camera incorporates a moving reflex member which permits a somewhat compact design but nevertheless succumbs to the disadvantages normally associated with reflex cameras incorporating movable reflex members. Typically, one such problem is the time delay between actuation of the camera's shutter release button and the exposure of the film unit located in position for exposure. During this time delay, the user of the camera must hold the camera relatively steady until the camera's shutter is closed. The viewfinder and/or rangefinder are conditioned to prevent the entry of actinic light into the interior of the camera until the reflex mirror or a reflecting member has moved to a position which will allow exposure of the film unit, and the camera's shutter has opened and closed to allow the exposure. Furthermore, the reflex member must move at such a speed that additional problems such as jerking of the camera caused by impact of the reflex member may occur.
Additionally, the mechanism necessary to move the reflex member between exposure and viewing mode positions is quite costly and complex so as to admit of both production and operational difficulties.
Conversely, certain photographic materials are structured such that the transfer image formed upon direct exposure of the film unit to a selected subject and processing will be geometrically non-reversed. Exemplary of such film units are those described in U.S. Pat. No. 2,983,606 entitled PROCESSES AND PRODUCTS FOR FORMING PHOTOGRAPHIC IMAGES IN COLOR and issued to H. G. Rogers on May 9, 1961, and U.S. Pat. No. 3,761,271 entitled FILM ASSEMBLAGE FOR COLOR DIFFUSION TRANSFER FILM and issued to H. G. Rogers on Sept. 25, 1973. Therefore, these film units are not compatible with a camera whose optical system only provides for an odd number of geometrical reversals.
Heretofore, it has been known to provide a camera with an optical system capable of geometrically reversing the image of a subject an even number of times onto one negative and an odd number of times onto a second negative, e.g., see U.S. Pat. No. 1,298,641 granted to Barnes et al. on Apr. 1, 1919. However, this type of camera does not teach the inventive concept of a camera which is adapted for use with both types of film units, i.e., those requiring an even number of geometrical reversals and those requiring an odd number to provide a non-reversed positive image in the film unit in response to a single exposure. To the contrary, cameras of the type shown by Barnes et al. use the same type of film for both exposures and two exposures are required to produce a scene which may be viewed by transmitted light. Obviously, the versatility of this type of camera is very limited.